Hi Eric
Regarding the 'cavalry' photograph. He still looks like an infantry man on a horse. The rifle is not a shorter carbine, but the infantry length Long Lee, and his puttees are wound like an infantry man - bottom to top, rather that top to bottom. But he is wearing a mounted man’s bandolier.
The replacement SMLE rifle was introduced in 1904, but it would have taken years to reach all regiments. Part-timers would have carried on using the Long Lee right up to WW2. That is the rifle used in Dad’s Army.
The weight of his tunic looks more Home than Overseas, and I think the hat was introduced in 1904.
Was he born c1886, so he was 25 in 1911 living in Alverstoke? If so he should have still been serving in WW1, but I cannot find a medal index card for him.
Ken